On 27/10/17 15:38, Martin McCormick wrote: > A perldoc of Device::SerialPort says that lookfor is > supposed to block or hold until a character string emerges from > the port as in /dev/ttyUSB0 or /dev/ttyS1. When I trace the > code, it just loops as fast as it can and never holds to wait for > anything. From my reading, if you call lookfor without any arguments, it will not block, but poll the device and return immediately. Examples using that behaviour have a sleep to stop it running away. If you want the blocking behaviour, give it the number of characters you're waiting for, and it will return only when it gets them. I'm looking at http://search.cpan.org/~cook/Device-SerialPort/1.04/SerialPort.pm#Methods_for_I/O_Processing Richard
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